(a) Field of the Invention
The invention described herein relates to novel compounds classified in the field of organic chemistry as propenes, useful as color-forming substances, particularly in the art of transfer imaging, pressure-sensitive and thermal-responsive carbonless duplicating; to transfer imaging systems containing said compounds; to pressure-sensitive and thermal-responsive carbonless duplicating systems containing said compounds and to processes for preparing said propenes.
(b) Information Disclosure Statement
Several classes of organic compounds of widely diverse structural types are known to be useful as colorless precursors for transfer imaging systems. Among the more important classes, there may be named leuco-type dyestuffs such as: phthalides, for example, crystal violet lactone, Malachite green lactone; fluorans, for example, 3-dialkylamino-7-dialkylaminofluoran, 3-dimethylamino-6-methoxyfluoran; phenothiazines, for example, benzoyl leuco methylene blue; Rhodamines, for example, Rhodamine B-anilinolactone; and spiro-dinaphthopyrans, for example, 3-methyl-spiro-dinaphthopyran. The classes of organic compounds listed above also generally find utility in pressure-sensitive and thermal-responsive carbonless duplicating systems.
Typical of the transfer imaging systems, is the system described in U.S. Pat. No. 4,399,209, which issued Aug. 16, 1983. In this patent, a transfer imaging system is disclosed wherein images are formed by image-wise exposing a layer comprising a chromogenic and pressure-rupturable material containing as an internal phase, a photosensitive composition. In this system, the chromogenic material is encapsulated with the photosensitive compound. Upon exposure to filtered U.V. or blue light in the wavelength range of 380 to 480 nanometers, a certain portion of the capsules will harden. The capsules in which the internal phase has remained liqid are ruptured and the chromogenic material is image-wise transferred to a developer or copy sheet where the chromogenic material reacts with a developer to form an image.
Typical of the many commercially accepted pressure-sensitive and thermal-responsive carbonless copy systems are those described in U.S. Pat. Nos. 2,712,507; 2,800,457; 3,041,289; and 4,000,087, which issued July 5, 1955; July 23, 1957; June 26, 1962; and Dec. 28, 1976, respectively.
Many of the color formers in the prior art suffer one or more disadvantages such as low tinctorial strength, low resistance to sublimation, low susceptibility to copiability of the color-developed images in standard office copying machines, for example, a xerographic type of copier, poor image stability in the presence of light, i.e., the product image fades losing intensity or changes to a less acceptable color, and low solubility in common organic solvents. The latter disadvantage requires the use of specialized and expensive solvents in order to obtain microencapsulated solutions of sufficient concentration for use in pressure-sensitive copying systems and transfer imaging systems.
The following items to date appear to constitute the most relevant prior art with regard to the instant invention.
Ricoh KK-owned Japanese Patent Publication No. 60,231,766, which was published Oct. 18, 1985, discloses compounds having the structural formula ##STR1## wherein R.sup.1 -R.sup.4 =lower alkyl; and R.sup.5 =H or lower alkyl. The compounds are disclosed as being useful as color formers for heat and pressure-sensitive recording paper capable of being read by an optical reader.
Ricoh KK-owned Japanese Patent Publication No. 60,230,890, which was published Oct. 16, 1985, discloses compounds having the structural formula ##STR2## wherein R.sup.1 -R.sup.4 are H or (un)substituted alkyl; R.sup.5 and R.sup.6 are H or (un)substituted phenyl; R.sup.7 is (un)substituted alkyl or (un)substituted phenyl.
The compounds are disclosed as being useful as color formers for heat- and pressure-sensitive recording paper capable of being read by an optical reader.